Heat Transfer for a Nuclear Reactor Review Heat Transfer

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Heat Transfer for a Nuclear Reactor
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Review Heat Transfer Terms

• Conduction-occurs across the medium
• 1
• Convection-occurs between a surface and a moving
  fluid
• 2
• Radiation Heat Transfer-occurs between two
  surfaces
• 3

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Subjects

• Heat generation
• Decay heat
• Transfer in the elements
• Plate
• Cylinder
• Transfer to the Coolant
• Coolant channels
• Other coolants
• Boiling Regimes
• Design Criteria
• Loss of Coolant Accident (LOCA)

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Heat Generation

• 200 MeV/ fission (ER)
• Ed Energy deposited in locally 180MeV
• Number of fissions in a core are a function of
  the FLUX(f)
• FLUX is a function of position in the core f(r,z)

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Heat Generation
r
z
H
R
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Decay heat

• Heat is released as the accumulated fission
  products decay
• The amount of heat is ? fission products ? to the
  power level

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Coolant Flow qw(hout-hin)
Recirculating
Steam Tout
Tout
q
q
Tin
WaterTin
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Plate fuel
ab
T(x)
a
a ab
X
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Cylinder
TF
z
Tc
Ts
a
Tmax
ab
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Transfer to the coolant

• For a Cylinder bltlta

Off the surface
coolant
fuel
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Coolant Channels

• Now you need to remember more heat transfer and
  fluid mechanics
• The heat transfer for a channel is

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Other coolants

• Gas cooled Helium
• Pebble bed in development
• Liquid sodium and potassium
• Need corrosive resistant structure

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Boiling Heat Transfer
Annular flow
Bulk boiling
Bubbly flow
T
Local boiling
ln q
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The Boiling Crisis
Full film
T
Partial film
Annular flow
ln q
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LOCA

• Address component breakdown or a combination of
  component breakdowns that lead to interruption of
  normal cooling
• When an interruption occurs, the fission process
  is terminated, however heat generation continues

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Classifications of operation

• Normal
• Operational transients
• Upsets
• Emergencies
• Limiting Fault Conditions includes Design basis
  accident DBA
• Unprotected or beyond DBA

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Engineered Safety Systems

• The actions are done as a result of instrument
  signals
• Reliability
• Duplication
• Diversity

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Most common ESS

• Alternate cooling
• SCRAM - Tripping - insert control rods to stop
  fission
• Control
• Cool
• Contain

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Some examples

• Millstone 1(660 MWe BWR) - corrosion of
  condensers leads to sea water to enter primary
  cooling circuit
• Browns ferry fire -(2 1065 MWe BWR 1 in
  construction) fire affected 2000 cables cause
  about 10 M
• Three mile island- relief valve stuck open
• Ginna 490 MWe PWR- rupture in a steam generator
  tube
• Mihama-2 - 500 MWe PWR rupture in a steam
  generator tube

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More examples

• Chornobyl-Chernobyl
• Chalk River - NRX- control rod/ operator error
  forerunner to the CANDU
• Windscale fire- UK large air cooled pile designed
  for Pu burst fuel cartridge
• St. Laurent - French
• Hunterston scotland - Seawater in the reactor
  vessel
• Hinckley point
• EBR-1 and Fermi -1 fast breeder.